Breast Cancer Prevention by Dietary Phytochemicals

描述(申请人提供)：这项临床前研究项目的总体目标是通过动物模型测定许多可食用十字花科蔬菜的成分异硫氰酸苄酯(BITC)预防乳腺癌的效果，并以MDA-MB-231和MCF-7人乳腺癌细胞为模型确定其抗癌作用的机制。这些研究的理论基础来自于最近的流行病学数据和我们初步研究的结果。流行病学研究得出结论，十字花科蔬菜的摄入量与乳腺癌风险呈负相关。我们的初步研究使我们推测，BITC可能延缓乳腺癌的发生和/或进展，因为它能够导致P53和CDC25C调节的G2/M期细胞周期停滞，以及caspase介导的涉及ROS生成和Bcl-2家族蛋白的细胞凋亡。这一假说将通过以下特定目标进行验证：特定目标1将确定BITC介导的ROS产生的机制，这对BITC诱导细胞凋亡至关重要(初步数据)。《特定目的2》将系统地确定BITC诱导的细胞凋亡过程中，BITC诱导的细胞凋亡中的Bcl2家族蛋白和caspase的作用。在具体目标3中，实验旨在回答野生型P53的表达是否加剧了BITC介导的细胞周期停滞，以及BITC介导的CDC25C蛋白下调是否是由关键半胱氨酸残基的氧化还原修饰(S)引起的。特异性靶点4将确定饮食BITC对裸鼠体内移植瘤MDA-MB-231和MCF-7生长的影响。特定目的5将确定饮食BITC给药对MMTV-neu转基因小鼠乳腺癌发生的影响。在特定的目标4和5中，将分析来自对照组和BITC处理组小鼠的肿瘤组织的细胞凋亡指数以及细胞周期和凋亡调节蛋白的水平，以深入了解BITC可能抑制体内乳腺癌发生的机制。总之，拟议的研究将(A)确定BITC抑制人类乳腺癌细胞生长的机制，这可能导致识别可能在未来临床试验中有用的基于机制的生物标记物，以及(B)在动物模型中确定BITC对乳腺癌的疗效，这是启动临床试验以确定其抗人类乳腺癌活性的先决条件。

DESCRIPTION (provided by applicant): The overall objective of this preclinical research project is to determine efficacy of benzyl isothiocyanate (BITC), a constituent of many edible cruciferous vegetables, for prevention of breast cancer using animal models and to determine the mechanism of its anti-carcinogenic effect using MDA-MB-231 and MCF-7 human breast cancer cells as a model. Rationale for these studies derives from recent epidemiological data and the results of our preliminary studies. Epidemiological studies have concluded that cruciferous vegetable intake is inversely associated with breast cancer risk. Our preliminary studies led us to hypothesize that BITC may delay onset and/or progression of breast cancer due to its ability to cause p53- and Cdc25C-regulated G2/M phase cell cycle arrest and caspase-mediated apoptosis involving ROS generation and Bcl-2 family proteins. This hypothesis will be tested by the following specific aims: Specific Aim 1 will determine the mechanism of BITC-mediated ROS generation, which is critical for apoptosis induction by BITC (preliminary data). Specific Aim 2 will systematically determine the role of Bcl-2 family proteins and caspases in BITC- induced apoptosis. In Specific Aim 3, experiments are designed to answer the questions whether expression of wild type p53 exacerbates BITC-mediated cell cycle arrest, and whether BITC-mediated down-modulation of Cdc25C protein is caused by redox modification of critical cysteine residue(s). Specific Aim 4 will determine the effect of dietary BITC administration on growth of MDA-MB-231 and MCF-7 xenografts in vivo in nude mice. Specific Aim 5 will determine the effect of dietary BITC administration on breast carcinogenesis using MMTV-neu transgenic mice. In Specific Aims 4 and 5, tumor tissues from control and BITC treated mice will be analyzed for apoptosis index and levels of cell cycle and apoptosis regulating proteins to gain insights into the mechanism by which BITC may inhibit mammary carcinogenesis in vivo. In summary, the proposed studies will (a) define the mechanism by which BITC inhibits growth of human breast cancer cells, which may lead to identification of mechanism-based biomarkers potentially useful in future clinical trials, and (b) determine efficacy of BITC against breast cancer in animal models, which is a prerequisite for initiation of clinical trials to determine its activity against human breast cancer.